Display devices include various types such as a liquid crystal display device and a plasma display device. As one type of these display devices, a display device using, as the light source of a pixel, organic electroluminescent elements (organic EL elements) has come to be put into practical use.
This type of display device includes a plurality of organic EL elements arrayed on a substrate. On the substrate, partition walls for dividing organic EL elements are disposed in a lattice pattern or a stripe pattern. Each organic EL element is provided in a region divided by the substrate and the partition wall. For example, when a plurality of partition walls are provided in a stripe pattern on the supporting substrate, each of the organic EL elements is arrayed in each space between the partition walls (also called a “concave portion”), and the organic EL elements that are arrayed respectively in a space between the partition walls are arrayed at a predetermined interval along an extending direction of the partition wall. In other words, the organic EL elements are arrayed in a matrix pattern. Further, for example, when the partition wall in a lattice pattern is provided on the supporting substrate, each organic EL element is arrayed in a region divided into a substantially rectangular shape by a lattice-patterned partition wall.
Referring to FIG. 3, the composition of a conventional light-emitting device is described. FIG. 3 is a view schematically illustrating a light-emitting device provided with a plurality of organic EL elements.
The organic EL element is composed by including a pair of electrodes and a plurality of predetermined layers provided between the electrodes. As the predetermined layer, the organic EL element includes at least one light-emitting layer. As illustrated in FIG. 3, the organic EL element is composed by stacking an anode 2, a hole injection layer 3, a hole transport layer 4, a light-emitting layer 5, and a cathode 6 in this order on a supporting substrate 1 so that the anode 2 is located near the supporting substrate 1.
The above-described predetermined layer can be formed by an applying method. For example, the hole injection layer 3 can be formed by supplying an ink including a material to be the hole injection layer to a region (concave portion) divided by a partition wall 7, and solidifying the ink. Thus, when the hole injection layer 3 is formed by the applying method, the supplied ink could be solidified while remaining wet-spread on a side face of the partition wall 7 in some cases. That is, as illustrated in FIG. 3, on the periphery of the hole injection layer 3 provided in the concave portion, a creeping-up portion 3a creeping up toward a direction that is away from the supporting substrate 1 could be formed along a side face of the partition wall 7 in some cases. When forming sequentially a hole transport layer 4, a light-emitting layer 5 and a cathode 6 on the hole injection layer 3 having such a creeping-up portion 3a, the creeping-up portion 3a and the cathode 6 could be physically connected with each other in some cases.
A material frequently used at present for the hole injection layer 3 has relatively low electric resistance. Therefore, when the creeping-up portion 3a and the cathode 6 are physically connected with each other, the cathode 6 and the anode 2 become electrically connected with each other through the creeping-up portion 3a, and as the result, a leakage current may be generated. A countermeasure for preventing the generation of such leakage current has been studied (for example, see Patent Literature 1). However, this countermeasure cannot necessarily be practical, so the improvement is desired.